Effect of Hypothermia on the Composition of Phenolics in Buckwheat Plants with Different Ploidy

Effect of hypothermia (5 degrees C; 1 and 7 days) on growth processes and accumulation of phenolic compounds in above-ground organs was investigated in buckwheat (Fagopyrum esculentum Moench) seedlings of di- and tertaploid genotypes. It was found that changes in all the examined parameters in the seedlings of the diploid genotype were more pronounced than in the tertaploid genotype. Under hypothermia, a reduction in the height of seedlings and the length of the root system as compared with control material, an elevation of the content of malonic dialdehyde, and a decrease in the content of total phenolics in the above-ground organs of diploid genotype in contrast to tertaploid were observed. Exposure to low temperature caused a reduction in the content of phenylpropanoids in buckwheat hypocotyls of both genotypes, whereas accumulation of anthocyans in most cases rose depending on the duration of chilling and genotype. At the same time, hypothermia did not cause changes in the content of phenylpropanoids and flavonoids in cotyledonary leaves of either genotypes, which remained on the level of control material. The activity of a key enzyme of phenolic metabolism L-phenylalanine ammonia lyase in above-ground organs of the seedlings exposed to hypothermia either did not change or decreased. Thus, investigation of the composition of phenolic compounds in buckwheat seedlings of two genotypes for the first time showed its dependence on the ploidy of cells and temperature conditions of plant growing.